Test swab and method of using same

ABSTRACT

A swab is impregnated with a test reagent such that a test for a specific substance can be effected by rubbing the impregnated swab over the surface to be tested and then viewing the swab for a reagent reaction. The swab may have a hollow stem, and within the hollow stem is a cartridge within another cartridge. An activator solution is in one of the cartridges and a reagent is in another of the cartridges. A method for testing for a substance includes impregnating a swab, and rubbing the swab over a surface suspected of containing the substance. If the substance is present in the surface, a reaction with the substance produces an easily detectable color on the swab tip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of applicationSer. No. 08/156,623, filed Nov. 24, 1993, now U.S. Pat. No. 5,364,792,which is a continuation-in-part of application Ser. No. 07/750,312,filed Aug. 27, 1991, now U.S. Pat. No. 5,330,917, which is acontinuation-in-part of application Ser. No. 07/709,981, filed Jun. 4,1991, and now abandoned, and which was a continuation of applicationSer. No. 07/499,488, filed May 7, 1990, now U.S. Pat. No. 5,039,618,which was a continuation-in-part of application Ser. No. 07/305,221,filed Feb. 2, 1989, now abandoned.

TECHNICAL FIELD

The present invention relates to a swab and a method of using the swabin a test for certain chemical elements, and more particularly, thepresent invention relates to a swab for retaining test reagents, amethod of using the same in a test for metals or other specific elementsor compounds, and a method of making the same.

BACKGROUND OF THE INVENTION

Contamination of the environment has been increasing steadily for yearsas the use of metals, chemicals, pesticides, and bacterial organisms hasincreased. Even though the toxicity of various metals has been known forcenturies, it is only recently that there has been a serious increase ininterest in minimizing human exposure to such metals. Current publicawareness of such pollutants and their associated hazards has created aconsumer demand for products that are capable of determining thepresence of unwanted and potentially dangerous materials.

Some of the more toxic metals include lead, cadmium, mercury, barium,chromium and beryllium. Lead, in particular, has been subject to muchattention due to its presence in articles or paints commonly found inthe home. See, for example, "A Simple Direct Estimation ofUltramicroquantities of Lead in Drinking Water Using Sodium Rhodizonate"by E. Jungreis and M. Nechama, Microchemical Journal, vol. 34, pp.219-221 (1986); U.K. Patent Application No. 2 025 047 A; "A SimplifiedMethod for Detection of Lead Contamination of Soil" by J. Preer and G.Murchison, Jr., Environmental Pollution (Series B), vol. 12, pp. 1-13;and "A Spot Test for Detection of Lead in Paint" by J. Sayre and D.Wilson, J. Pediatrics, vol. 46, pp. 783-785 (1970).

Chromium is also a toxic metal and is a known carcinogen. RegulationNews. Aug. 1994. pp. 47-48. Chromium occurs in public drinking watersupplies from cooling towers, waste water plants, plating operations,the tanning industry and some paint pigments.

As the titles of some of the prior art publications indicate, there is arecognized need in the industry for a simple or simplified test ormethod for determining the presence of lead and other toxic metals.However, as will become apparent from the remaining descriptions of theprior art, prior to the present invention, an effective and simple testfor lead and other metals had not been developed.

In a popular prior art method of detecting lead in paint, sodium sulfide(Na₂ S) is reacted with lead to form lead sulfide (PbS), a blackprecipitate. The presence of lead is thus confirmed by the appearance ofthe black precipitate, lead sulfide. This method has severaldisadvantages: (1) the sodium sulfide is potentially toxic, especiallyto young children; (2) the black precipitate is difficult to see on darksurfaces; (3) the sodium sulfide releases volatile hydrogen sulfide (H₂S), which has a noxious odor; and (4) the reagents react with manycations to form black precipitates and thus tends to give false readingson many metallic surfaces.

Another common analytical reagent is a metal complexing agent,rhodizonic acid. For over forty years, rhodizonic acid and salts thereofhave been used as analytical reagents to detect heavy metals, includinglead, in both qualitative and quantitative analyses. The methodology forusing rhodizonate dye is based on two types of tests:

(1) a quantitative determination of heavy metals in solutions using aspectrophotometer to obtain quantitative information; and

(2) qualitative determinations which use filter papers impregnated withthe reagent.

In addition, semi-quantitative information can be derived from the useof columns packed with silica gel impregnated with rhodizonate dye. SeeU.K. Patent Application No. 2 025 047 A.

The Macherey-Nagel Company (Duren, Germany) manufactures a test paperfor the determination of lead under the trademark PLUMBTESMO. ThePLUMBTESMO strips comprise a heavy filter paper with a reagentimpregnated therein. To test for lead in a solution, a strip is dippedinto the solution, and observed for a color change that indicates thepresence of lead. The PLUMBTESMO strips can also be used to detect leaddeposits in motor vehicle tailpipes.

The instruction sheet that is distributed with the PLUMBTESMO stripsindicates that the PLUMBTESMO strips may be used to detect the presenceof lead on a degreased surface. However, the instruction sheet impliedlyrecognizes that the PLUMBTESMO strips are not entirely satisfactory fortesting for the presence of lead on a surface. Specifically, theinstruction sheet indicates that the PLUMBTESMO strip may have to beheld firmly against a test surface for as long as fifteen minutes beforean indication of lead develops. Clearly, for nonprofessional, householduse, a test strip that must be held firmly for fifteen minutes isentirely unsatisfactory in that many users will become impatient afteronly a few minutes and will discontinue the application of thePLUMBTESMO strip against the test surface. That type of usage may, ofcourse, result in dangerous false readings, leaving the user with theerroneous impression that lead is not present when in fact lead may bepresent.

A further disadvantage of the PLUMBTESMO strips is that the testoperator must directly handle the test strips, thus being unnecessarilyexposed to chemicals. Yet another disadvantage of the PLUMBTESMO stripsis that the strips are flat and comparatively stiff, and are thus notreadily conformable to curved or otherwise unusually contoured surfaces,such as those that one is likely to encounter on moldings in olderhouses.

Thus, it should be clear that the lead tests, known prior to the presentinvention, are not entirely satisfactory.

Although not a test for lead, U.S. Pat. No. 4,707,450 discloses abiological specimen collection and test unit. The teachings of U.S. Pat.No. 4,707,450 are quite different from the present invention. Insummary, U.S. Pat. No. 4,707,450 discloses a specimen collection devicethat utilizes a swab to collect biological specimens for testing afterthe swab has been removed from the specimen collection location. Sincelead and other metals do not readily collect on a swab when rubbed on ametal-containing surface, the disclosed swab is not useful for testingfor metals. This is especially true because the success of the disclosedswab depends upon the removal of a specimen from the collection site forsubsequent testing. Because metals will not usually collect on the swab,the swab will not work well for metals testing.

Thus, there is a need in the art for a test or method for determiningthe presence of toxic metals, such as lead and cadmium. While leadtoxicity is better known, cadmium is toxic by inhalation of dust or fumeand is a carcinogen. Cadmium plating of food and beverage containers hasled to outbreaks of gastroenteritis or food poisoning. Other metals arejust as toxic. Thus, a simple test for metals and other toxic substanceswould serve to protect consumers from the toxic effects caused thereby.

SUMMARY OF THE INVENTION

Briefly described, the present invention relates to a swab that isimpregnated with a test reagent such that a test for a specificsubstance can be effected by rubbing the impregnated swab over thesurface to be tested and then viewing the swab for a reagent reaction.

The present invention also relates to a device for testing for asubstance on a surface including a cartridge, two compartments withinsaid cartridge containing a reagent and an activating solution,respectively, and an absorbent ball of material mounted on at least oneend of the cartridge. The reagent and activating solution are combinedand mixed within the cartridge before the device is used.

The invention also relates to a method of making a device for testing asubstance on a surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may more easily be understood by reference to thedrawings, wherein:

FIG. 1 is a view in cross section of a swab according to the presentinvention prior to the insertion of a reagent.

FIG. 2 is a view in cross section of a swab according to the presentinvention with a reagent inserted therein.

FIG. 3 is a view in cross section of a cartridge swab according to thepresent invention containing a cartridge and loose powder.

FIG. 4 is a view in cross section of a cartridge swab according to thepresent invention containing buffer and a cartridge containing dye.

FIG. 5 is a view in cross section of a cartridge swab according to thepresent invention containing two cartridges side by side.

FIG. 6 is a view in cross section of a cartridge swab according to thepresent invention containing two cartridges end to end.

FIG. 7 is a view in cross section of a dual swab according to thepresent invention with a reagent inserted therein.

FIG. 8 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing a cartridge and loosepowder.

FIG. 9 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing buffer and a cartridgecontaining dye.

FIG. 10 is a view in cross section of a cartridge with a dual swabaccording to present invention containing two cartridges side by side.

FIG. 11 is a view in cross section of a cartridge with a dual swabaccording to the present invention containing two cartridges end to end.

FIGS. 12 and 13 are views of embodiments of the present invention usingmicroencapsulation.

FIG. 14 is a view of an embodiment having a cartridge within acartridge.

FIG. 15 is a view of another embodiment having a cartridge within acartridge.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The subject matter of U.S. Pat. Nos. 5,239,618, 5,278,075 5,330,917, and5,364,793, is hereby incorporated by reference.

The test swabs of the present invention may be used to detect a varietyof substances on a variety of surfaces depending on the reagentcontained in the swab, including but not limited to, paint, ceramics,dust, soil, plant leaves, solder, bird cages, etc. The test swabs may beused to determine the presence of lead, cadmium, bismuth, mercury,cobalt, arsenic, tin, antimony, iron, aluminum, selenium, copper ororganophosphate. The test swabs may also be used to determine thepresence of chromium and chromate ions, nickel, manganese, zinc, barium,strontium, silver and vanadium. The present invention preferably will beused to determine the presence of metals in such surfaces.

The swabs can be made in a variety of formats as shown in the Figures,which are described below.

Referring now in detail to the drawings, wherein like reference numeralsrefer to like elements throughout, in the embodiments of FIGS. 1 and 2,a swab is indicated generally by reference numeral 10. The swab 10includes a stem 12 that is preferably formed from a hollow tube. Theswab also may include a handle or grip portion. The stem 12 may be madefrom glass, plastic, or any other suitable material. If plastic is used,the composition of the plastic is not critical. However, because glassis breakable and because plastic is more easily crimped, plastic ispreferable to glass.

In an alternative embodiment of the present invention, a solid stem maybe used.

At one end of the stem 12, a ball 14 of absorbent material is affixed.The absorbent material may be comprised of any number of materials,including, but not limited to: cotton fibers, rayon fibers, dacronfibers, monofilament polyester, monofilament nylon, other fibrouspolymeric compositions, or a porous or open cell structure such aspolyurethane foam. Table I lists several commercially available swabs,together with the source or manufacturer of each swab.

                  TABLE I                                                         ______________________________________                                                             STICK    STICK                                           ABSORBENT APPROX.    MA-      DIAM-                                           MATERIAL  DIAMETER   TERIAL   ETER   SOURCE                                   ______________________________________                                        Cotton    0.25"      Plastic  3/16"  J&J                                      Cotton    0.25"      Wood     Solid  CitMed                                   Cotton    0.50"      Wood     Solid  CitMed                                   Rayon     0.25"      Plastic  3/16"  CitMed                                   Rayon     0.50"      Plastic  5/16"  CitMed                                   Dacron    0.25"      Plastic  3/16"  CitMed                                   Nylon                                Coventry                                 Polyester 0.25"      Plastic  3/16"  Coventry                                 Polyester/                           Coventry                                 cellulose                                                                     Polyurethane                         Coventry                                 Porous                               Plastic                                  Plastic                              Interflo                                 Foam dauber                          Metal                                                                         Super                                                                         Brush Co.                                Wood dauber                                                                             0.75"                      Metal Nat'l                                                                   Novelty                                                                       Brush Co.                                ______________________________________                                    

For purposes of testing for lead, the preferred reagent dye isrhodizonic acid. Table II lists various dyes that are acceptable,together with the supplier or manufacturer of each.

                  TABLE II                                                        ______________________________________                                        DYE                SUPPLIER                                                   ______________________________________                                        Rhodizonic acid, potassium salt                                                                  Sigma Chemical Company                                     Rhodizonic acid, sodium salt                                                                     Sigma Chemical Company                                     Rhodizonic acid, disodium salt                                                                   Sigma Chemical Company                                     Rhodizonic acid, disodium salt                                                                   Eastman Kodak Company                                      ______________________________________                                    

No major differences in purity or other analytical criteria werereported for similar salts. The above materials all function well intesting for the presence of lead, as indicated below. An activatorsolution, described below, typically will be used with the reagent dyesin carrying out embodiments of the present invention.

For purposes of testing for cadmium, the preferred reagent dyes are4-nitronaphthalenediazoamino-azo-benzene or1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine. The latter dye may beobtained from Aldrich as Cadion.

Other substances may be tested for using the reagents and activatingsolutions listed in Table

                  TABLE III                                                       ______________________________________                                               Dye (Reagent which                                                     Sub-   Reacts with    Activating                                              stance Substance      Solution      Color                                     ______________________________________                                        Bi     Cinchonine - KI                                                                              Dilute acid   Orange                                           (1%)                         Red                                       Hg     1) Diphenylcar-                                                                              0.2 M HNO.sub.3                                                                             Violet                                           bazide (1% in                                                                 alcohol)                                                                      2) Cobalt (II) Cobalt (II)   Deep                                             thiocyanate test                                                                             acetate       blue                                      Sb     1) Rhodamine B Sb.sup.+5     Blue                                             (Tetraethyl-   nitrite                                                        rhodamine)                                                                    2) Phosphomolybdic                                                                           Sb.sup.+3     Blue                                             acid                                                                   Fe     1) 2,2'-bipyri-                                                                              Thioglycolic  Red                                              dine or 1,1'   acid buffer                                                    phenanthro-                                                                   line                                                                          2) 3-(2-pyridyl)-                                                                            1,2,4-triazine,                                                                             Purple                                           5, 6-bis(4-phenyl-                                                                           sodium salt                                                    sulfonic acid)                                                         Al     1) Aurin       NaOH          Red                                              tricarboxylic acid                                                            2) Quinolizarin                                                                              Ammonia, then Red                                                             glacial HONC                                            Se     Pyrrole reagent                                                                              0.5M iron (III)                                                                             Green-                                                          chloride; H.sub.3 PO4                                                                       Blue                                      organo-                                                                              Phosphomolybdic                                                                              1) K.sub.2 SO.sub.8 +                                                                       Blue                                      phos-  acid formed with                                                                             K.sub.2 SO.sub.4                                        phates sodium molybdate                                                                             2)Ascorbic Acid                                         Cu     1) Quinolyl    20 g Na acetate                                                                             Red                                              reagent (0.2 g/l                                                                             10 g K Na tartrate                                             in amyl alcohol)                                                                             3 g hydroxyl-                                                                 ammonium Cl                                                                   (all in 100 ml                                                                H.sub.2)O                                                      2) Dithiooxamide             Dark-                                            (1% in acetone)              Green                                            (Rubeanic acid)                                                        Co     Rubeanic acid  Ammonia/alkali                                                                              Brown                                                           tartrates                                               As     Magnesium      Silver nitrate                                                                              Red                                              nitrate/ammonium                                                              chloride                                                               Sn     Sodium sulfide dilute acid   Brown                                                                         (Sn.sup.+2)/                                                                  Yellow                                                                        (Sn.sup.+4)                               Cr     1) Diphenylcarba-                                                                            HCl or HNO.sub.3                                                                            1) Red-                                          zide                         violet                                           2) Chromotropic                                                                              HCl or HNO.sub.3                                                                            2) Red                                           acid                                                                   Ni     1) α-nitrose-β-                                                                   1) ethanol and                                                                              1)Brown                                          naphthol       acetic acid                                                    2)dimethylglyoxime                                                                           2) ethanol and                                                                              2)Red                                                           acetate or                                                                    tartrate buffers                                        Mn     sodium bismuthate                                                                            nitric acid or                                                                              Purple                                                          sulfuric acid                                           Zn     Mercury (II)   sulfuric acid or                                                                            Purple                                           chloride, ammonium                                                                           acetic acid                                                    thiocyanate and                                                               copper sulfate                                                         Ba     Sodium rhodizonate                                                                           Neutral buffer                                                                              Reddish                                                                       brown                                     Sr     Sodium         Neutral buffer                                                                              Reddish                                          rhodizonate, opt.            brown                                            potassium chromate                                                     Ag     p-             Nitric acid   Red-                                             dimethylaminobenzy           violet                                           lidene-rhodanine                                                       V      Tannic acid    Ammonium acetate                                                                            Deep                                                                          blue or                                                                       black                                     ______________________________________                                    

Several granular and particulate solids were tried as diluents orfillers for the dyes to be used in the swabs. While fillers are notrequired, they are useful to provide bulk to the dye when the dye is asolid so the dye can be placed in the swabs more conveniently since thedye is used in a small amount. No filler is needed when the dye to beused is a liquid. The filler material may be any material which does notadversely affect the desired reaction. All of the materials listed inTable IV can be used as a filler for the dyes used in the test method ofthe present invention, but some exhibited more desirable properties thanothers. The more granular and less sticky solids are preferable to usewith automatic filling equipment, such as a Kinematics Powder FillingMachine, model no. 1700 equipped with a model 3015 filling gun.

Table IV identifies several fillers and their ease of use with automaticfilling equipment.

                  TABLE IV                                                        ______________________________________                                        FILLER            RECOMMENDATION                                              ______________________________________                                        Alumina, acid     Worked well with the                                                          machine and filling gun                                     Talc              Worked well with the                                                          machine and filling gun                                     Silicic acid      Formed a plug, but worked                                                     with the machine and                                                          filling gun                                                 Glass beads       Formed a plug, but worked                                                     with the machine and                                                          filling gun                                                 Polyvinylpyrrolidone                                                                            Not recommended for use                                                       with the filling equipment                                  ______________________________________                                    

The rhodizonate dye is unstable in an aqueous medium. As a result,hygroscopic fillers may retain moisture too avidly and will consequentlycontribute to inactivation of this dye.

Table V identifies several materials capable of use as a filler for thedye, together with comments concerning the suitability of each material.

                  TABLE V                                                         ______________________________________                                                     APPEAR-                                                          BULKING AGENT                                                                              ANCE        COMMENTS                                             ______________________________________                                        Alumina                  Loose, sandy; mixes                                  WB-2, basic              well; fills tube                                                              easily                                               hygroscopic,                                                                  WA-1, acidic Loose       Mixes well;                                                                   hygroscopic, fills                                                            tube easily                                          WN-3, neutral                                                                              Loose       Mixes well;                                                                   hygroscopic, fills                                                            tube easily                                          Bentonite                Particulate; colored                                                          powder; unsuitable for                                                        use                                                  Cellulose                                                                     SigmaCell 20 Loose       Mixes well; fills tube                                                        easily                                               SigmaCell 50 Loose       Mixes well; fills tube                                                        easily                                               Florisil     Granular    Mixes poorly with dye;                                                        fills tube eabily                                    Fuller's Earth           Large pieces;                                                                 particles too large to                                                        use                                                  Fumed Silica Fluffy      Too fluffy; mixes                                                             poorly; hard to use                                                           for filling                                          Glass Beads  Sandy       Mixes with dye poorly;                                                        fills tube easily                                    Gum Acacia   Loose       Mixes well; fills tube                                                        easily                                               Mannitol     Clumpy      Hygroscopic, dye mixes                                                        well                                                 Polyvinylpyrrolidone     Granular; mixes                                      (PVP)                    poorly; unsuitable for                                                        filling machine                                      Silicic Acid Loose       Dye does not mix well;                                                        fills tube easily                                    Starch                                                                        Potato*      Loose       Mixes well; turns                                                             dark; does not fill                                                           easily                                               Wheat        Loose       Mixes well; does not                                                          fill tube easily                                     Talc         Powder      Mixes with dye                                                                moderately well fills                                                         tube easily                                          Zeolite      Fluffy Powder                                                                             Turns blue with the                                                           dye                                                  Zeolite mixture                                                                            Fluffy Powder                                                                             Turns blue with the                                                           dye                                                  ______________________________________                                         *Potato starch is susceptible to oxidation, and turns black on reaction       with iodine. Rhodizonate reacts with potato starch as iodine does.       

Accordingly, alumina (all types), talc, gum acacia, silicic acid, andmannitol are all suitable materials for use as a diluent with the dye.However, other materials in accordance with the spirit of the presentinvention may be used.

The swabs 10 are filled through the open end 16 of the stem 12,preferably with automatic filling equipment, such as that describedabove. Once the desired quantity of dye and filler 20 is inserted intothe swab 10, the end 16 of the stem 12 may be crimped as shown at 18 inFIG. 2. In the embodiment of FIG. 7, a ball of absorbent material 14 isinserted after the swab 10 is filled to provide a dual swab system.

In another embodiment, the swabs are filled with a dye/filler mixtureusing a Kinematics dispensing machine to fill. Then, the solid filledswabs are shaken on a vibrating table to disperse the solid throughoutthe swab. A four inch wooden applicator is inserted into the swab toprevent loss of reagent through the open end and a drop of glue from aglue gun then is applied to the end of the unit. In the dual swabembodiment of FIG. 7, an absorbent ball is added to the end of the swab.Automatic filling units can be designed by using a metal brace notchedwith the appropriate size holes to ensure that the swabs remain in afixed position during an automatic filling operation. A conveyor beltcan move these units under a fixed dispensing gun. After the dispensingof the solid reagent, the swabs can be sealed by a variety of automaticprocedures including, melting to close, using pressure to close andflattening the plastic handle of the swab.

In various tests, swabs were filled with 20, 30, 40, and 80 mg. of thedye and filler. In such tests, the ratios of filler to dye were variedbetween 0 and 100:1.

In use, the absorbent ball 14 of the filled swab 10 is wetted with anactivator solution. A pH level of between about 2.0 and about 3.0 ispreferable for the lead-rhodizonate reaction. For the lead reaction, abuffer generally is used as the activator solution. A pH level of 2.8for the buffer is optimal for the lead-rhodizonate reaction. The wettedabsorbent ball 14 is then rubbed onto a surface suspected of containinglead. If lead is present on the surface, a reaction occurs with therhodizonate dye, thus causing an easily detectable deep pink color toappear on the absorbent ball 14 of the swab 10. The test is evensensitive enough to detect lead dust on a surface caused by sandinglead-containing paint, even after the surface had been vacuumed andwashed with trisodium phosphate detergent.

For the cadmium reaction, the activator solution generally will comprisesodium tartrate, sodium acetate, sodium citrate, potassium hydroxide ora mixture thereof. Additional chelating materials such as EDTA may alsobe present. The pH preferably used for the cadmium reaction is aboveabout 8, more preferably above 9. The potassium hydroxide may be used toadjust the pH. Bases other than hydroxide, which form insoluble cadmiumcomplexes such as carbonate might be used. When testing for cadmium, thearea to be tested is rubbed with the swab containing the reagent andactivator solution. If the swab becomes pink, cadmium is present.

The colorimetric reaction to detect chromium is based on a redoxreaction between chromate ions and diphenylcarbazide. In acid solution,chromate ions oxidize diphenylcarbazide to diphenylcarbazone which isfurther oxidized to diphenylcarbadiazone which has keto and enol forms.The divalent chromium ions formed by the overall reaction, react withthe enol form of diphenylcarbazone to yield a red-violet complex.

To test for chromium III ion, chromium must first be oxidized to thechromate ion (CrO₄ ²⁻) by one of several different methods, usingalkaline hydrogen peroxide, alkaline perborate solution, alkalinepotassium or ammonium peroxodisulfate, or bromine water in alkalinesolution. A positive test for chromium would be reflected in a positivetest for chromate ion as described in the examples below.

The pH to be used with detection of other metals and substances will bereadily determined by one of ordinary skill in the art from the reagentsand activating solutions disclosed in Table III and the Examples below.

INTERFERENCES CAUSED BY OTHER CATIONS

Many cations form complexes with rhodizonate. However, the specificconditions for optimal reaction of most cations are different from thoserequired for lead. Only barium and lead form a red or deep pink complexunder the conditions defined for the swab tests. The color formed by thereaction with barium is red-brown and thus to a skilled technician isdistinguishable from the color formed during the reaction with lead.However, to avoid confusion, the reaction with barium can bedistinguished from the reaction with lead with the use of sodiumsulfide. A drop of sodium sulfide (7.5%) on top of the developed pinkswab changes the swab to black in the presence of lead by forming leadsulfide. The precipitate formed by the reaction between sodium sulfideand barium is not black, i.e., sodium sulfide does not change to blackin the presence of barium alone.

The solid fill method, described above with the use of a Kinematicsfilling machine, is the manufacturing option that is best for preservingthe stability of the dye reagent. However, alternative manufacturingprotocols are also available.

In an alternative method of preparation of a swab for a lead test, anaqueous solution of 0.01 2M rhodizonate (dye) is prepared. Therhodizonate solution may be prepared using a tartrate buffer at pH 2.8.Although that pH level is the preferred level for the lead testingreaction, at that pH level, the rhodizonate dye is unstable andcompletely degrades in about thirty-six hours. As an alternative, therhodizonate solution can be prepared using water at pH 5 or 6. At thatpH level, complete degradation of the rhodizonate takes about ninety-sixhours.

The addition of some organic solvents may enhance the stability of theaqueous rhodizonate solution. For example, 10 to 20% methanol, ethanol,or acetone may be added.

Within one hour of preparation of the solution, swabs are dipped in thesolution for thirty seconds to one minute. The swabs are then rapidlyfrozen in acetone/dry ice, or liquid nitrogen, and dried bylyophilization. The swabs can then be used in the same manner as theswabs that are filled from the inside with a filling machine. The swabscan alternatively be dried under heat, although the temperature must bekept below 80° C.

In another embodiment, the swabs can be pretreated by soaking theabsorbent material of the swabs in a tartrate buffer, pH 2.8, or anyother buffer with a pH preferably between 2 and 3. The soaked swabs arethen dried under heat.

Since other cations might interfere with a test for lead, the swab canalso be presoaked in a buffer containing EDTA for about one minute inorder to clean other possible interfering cations from the swab prior tothe test. The EDTA can be included in the buffer described in thepreceding paragraph.

In one preferred embodiment, the swab of the present invention isprepared as a cartridge swab. In this embodiment, a device for testingfor a substance or metal on a surface comprises a cartridge, at leasttwo compartments within the cartridge wherein one compartment contains areagent that reacts with the metal and the other compartment contains anactivating solution, and an absorbent ball of material mounted at leastone end of the cartridge. The reagent and activating solution arecombined and mixed within the cartridge before the device is used. Thisembodiment can take several forms, some of which are shown in FIGS. 3-6,8-11, and 14-15.

The simplest design of the cartridge swab is a system wherein twocompartments are used. One compartment contains an activator solutionand the other contains a dye. When testing for lead, the activatorsolution will be the buffer solution described above and the dye will berhodizonate dye. When testing for cadmium, the activator solution willbe sodium tartrate, sodium acetate, sodium citrate, potassium hydroxideor mixtures thereof, and the dye will be4-nitronaphthalene-diazoamino-azo-benzene or1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine. The absorbent ballmounted at one end of the cartridge swab may be attached when thecartridge swab is prepared or it may be attached when the cartridge swabis to be used. Where there is an absorbent ball at each end of thecartridge swab, one end is closed with an absorbent ball, the cartridgeswab is filled and then the other absorbent ball is attached when thecartridge swab is prepared or when it is to be used.

FIG. 3 shows an embodiment of a cartridge swab wherein a breakablecartridge 22 contains a small amount of activator solution. Thebreakable cartridge 22 is inserted into a plastic holder or cartridge 24into which dry dye powder 26 plus any additives required for the testdesired has been dispensed. The swab tip 14 generally will be placed onthe cartridge 24 before the cartridge 24 is filled with dry dye powder26 and the breakable cartridge 22. When the cartridge swab is to beused, the breakable cartridge 22 is broken and the activator solutionmixes with the dye powder and wets the swab tip. The swab tip then canbe rubbed over the surface to be tested. As shown in FIG. 8, thisembodiment may also be utilized in the dual swab configuration.

FIG. 4 shows an embodiment of a cartridge swab wherein a small breakablecartridge 28 is prepared containing dry dye powder plus any additivesrequired for the desired test. The cartridge 28 is placed inside anotherbreakable cartridge 32 large enough to hold cartridge 28 and sufficientactivating solution 34 to execute the desired test. The breakablecartridge is broken when the test is to be performed and the activatingsolution mixes with the dye and wets the swab tip which can be rubbedover the surface to be tested. As shown in FIG. 9, this embodiment mayalso be utilized in the dual swab configuration.

FIG. 5 shows an embodiment of the cartridge swab wherein two breakablecartridges are used side by side in a larger cartridge. Breakablecartridges 36 and 38 will contain either activating solution or dye. Thecartridges are broken together when the test is to be performed and theactivating solution mixes with the dye and wets the swab tip which canbe rubbed over the surface to be tested. As shown in FIG. 10, thisembodiment may also be utilized in the dual swab configuration.

FIG. 6 shows an embodiment of the cartridge swab wherein two breakablecartridges 36 and 38 are used in an end to end format inside a largercartridge 40 which has a swab tip 14. The cartridges are broken togetherwhen the test is to be performed and the activating solution mixes withthe dye and wets the swab tip which can be rubbed over the surface to betested. As shown in FIG. 11, this embodiment may also be utilized in thedual swab configuration.

In the dual swab embodiments of FIGS. 8-11, the compartments mustcontain enough reagent and activating solution to wet the absorbentballs at each end of the cartridge swab. This may require using anadditional amount of each reagent in the cartridges over the amountneeded for the monoswab embodiments. One of ordinary skill in the artwill readily be able to ascertain the amounts needed for a dual swabcartridge from the examples below for the monoswab embodiments.

FIG. 14 is a view of an embodiment of a cartridge swab having a stem 50and a swab tip 60. Inside the stem 50 is a breakable cartridge 52, whichcontains a small amount of activator solution 54. The breakablecartridge 52 also includes a smaller breakable cartridge 56 inside thecartridge 52. The inner cartridge 56 includes a dye 58, such as a drydye powder, plus any additives that might be required. When the swab isto be used, the cartridges 52, 56 are broken and the activator solutionmixes with the dye inside the stem 50 and wets the swab tip 60. The swabtip 60 then can be rubbed over the surface to be tested. This embodimentmay also be utilized in the dual swab configuration, wherein a swab tipis placed at each end of the stem 50.

FIG. 15 is a view of an embodiment of a cartridge swab having a stem 62and a swab tip 72. Inside the stem 62 is a breakable cartridge 64, whichcontains a small amount of dye 66, such as a dry dye powder, plus anyadditives that might be required. The breakable cartridge 64 alsoincludes a smaller breakable cartridge 68 inside the cartridge 64. Theinner cartridge 64 includes an activator solution 70. When the swab isto be used, the cartridges 64, 68 are broken and the activator solution70 mixes with the dye inside the stem 62 and wets the swab tip 72. Theswab tip then can be rubbed over the surface to be tested. Thisembodiment may also be utilized in the dual swab configuration, whereina swab tip is placed at each end of the stem 62.

The activator solution and the reagents used in the embodimentsdisclosed in FIGS. 14 and 15 may be any of those disclosed herein, orany other suitable materials generally known to those of ordinary skillin the art.

In a further embodiment, more than two compartments are provided toallow the necessary amount of reagent and activating solution to bepresent in the cartridge swab. For example, four cartridges may be usedto supply the necessary reagent and activating solution to each end ofthe cartridge swab.

In a further embodiment of the present invention, only one end of thecartridge is closed with an absorbent ball and the other end of thecartridge is closed with abrasive paper or board material. Thisembodiment is preferred for use on surfaces which need to be roughenedin order to get good contact between the absorbent ball and the surface.The cartridge swab can be used to first roughen the surface with theabrasive paper, and then test the surface for a substance or metal withthe end of the cartridge swab having an absorbent ball.

The swab tips on the cartridge swabs can be the same type of swabsdescribed above for use on the stick type swabs.

The cartridges which are used to hold the breakable cartridgescontaining the reactants for the desired test can be nonbreakable orsqueezable containers. For example, a squeezable cartridge similar to atoothpaste tube may be used. The breakable cartridges are placed insidethe squeezable cartridge and the end is closed with a fibrous or porousswab tip. The swab tip optionally may have a pointed tip which breaksthe cartridges contained within the tube. The squeezable cartridge issqueezed, breaking the cartridges within the squeezable cartridge andmixing the reagents. The reagents wet the swab tip which can then berubbed over the surface to be tested.

The breakable or squeezable cartridges contained within the cartridgeswabs may be glass, plastic or other material which will open uponcrushing or squeezing. Where glass cartridges are used, the unit willpreferably contain spacers between the cartridges to prevent prematurebreakage of the glass cartridges, allowing reagents to mix prior to thedesired time for use. When plastic cartridges are used, any type ofplastic which will open on application of pressure is satisfactory. Thisplastic may be rigid and brittle, such as butyrate tubing, polymethylpentene or polystyrene or flexible, such as low density polyethylene,polyallomer, or polyvinyl chloride. Flexible plastic containers areadvantageous since there is no glass to break and no pieces of glasswhich may come through the outer package. Such flexible plasticcartridges may be sealed using an ultrasonic sealing technique so thatgentle pressure will break the seals opening the reagent cartridges,releasing the materials contained inside.

Another method of the present invention for testing for a metal on asurface includes the steps of providing a swab stick having a stem andan absorbent ball of material at one end of the stem, wherein theabsorbent ball of material is impregnated with an activating solutionthat reacts with the metal. The surface is then contacted with theimpregnated absorbent ball of material, and the absorbent ball ofmaterial is further impregnated with a reagent that reacts with themetal in such a manner so as to give a visual indication of thereaction. The presence of metal on the surface may be detected byinspecting the impregnated ball of material for the visual indication.Such a method may be used to detect, among other metals, chromium,nickel, manganese, zinc, barium, strontium silver and vanadium.

The test swabs are preferably packaged in test kit packets which includeat least one and, more preferably, several swabs. For test kits forlead, the test kit will preferably also contain a control tube filledwith sodium sulfide. As discussed above, sodium sulfide reacts with manycations to form black precipitates and may give false readings when usedas a test for lead. However, it has been found useful to include acontrol tube containing sodium sulfide in the test kits for lead inorder to enable the user of the test kit to double check the results ofthe other test swabs. The inclusion of a sodium sulfide control may alsobe useful where the user desires to test for lead on plaster and stuccosurfaces. Since these materials may contain sulfates, the reagents usedin the test swabs according to the present invention may be blocked fromreacting with lead in the plaster or stucco surface to produce a visiblereaction. The sodium sulfide tube is provided to allow the user to checkthese surfaces with the same kit as used for other surfaces.

In one preferred embodiment, the test kit will contain an insert cardwhich has been coated in at least one area with a lead or othermetal-containing material. For example, a cardboard or paper boardinsert may be prepared with one or more circles or patches of lead orother metal-containing material coated thereon. If a user of the testkit obtains negative results with the test swabs in the kit when theswabs are applied to the surface of interest, the user can rub the swabsover the areas of metal-containing material on the insert card to verifythe accuracy of the test. If the swabs indicate the presence of lead orother metal when contacted with the card containing such material, theuser is assured that the negative results obtained were correct.

The test kit according to the present invention comprises at least onedevice for testing for a substance on a surface, comprising a cartridge,at least two compartments within the cartridge wherein at least onecompartment contains a reagent that reacts with the substance and atleast one other compartment contains an activating solution, and anabsorbent ball of material mounted at at least one end of the cartridge.The reagent and activating solution are then combined and mixed withinthe cartridge before the device is used.

In a preferred embodiment, the test kit further comprises at least onetube for dispensing sodium sulfide. The tube for dispensing sodiumsulfide may be any type of tube or dropper for dispensing materials.Preferably, the tube will be a test swab according to the presentinvention.

In a preferred embodiment, the test kit further comprises an insert cardcoated in one or more areas with the substance for which the kit isintended to test. The insert card may by cardboard, paper board or anyother material capable of being coated with the desired material.

As an alternative to the embodiments using one or two cartridges, therecan be a plurality of compartments containing reagents. In oneembodiment, the compartments are micro-compartments such as those formedby microencapsulation. The micro-compartments can be formed by anymethod known to those of skill in the art of microencapsulation. SeeFIG. 12.

FIG. 13 illustrates another embodiment utilizing microencapsulationhaving a liquid layer 42, a solid layer 44, and a liquid permeableabsorbent pad, 46. In a further embodiment, the liquid layer and thesolid layer may be reversed.

The following examples are provided to further illustrate the invention,but are not meant to limit the scope of the invention in any way.

EXAMPLES TESTS TO DETERMINE PREFERRED RATIOS OF FILLER TO DYE Examples Ithrough XIII

In examples I through XIII, swabs were obtained from CitMed having anabsorbent ball of 0.50 inch diameter made from rayon fibers. The swabstem was a 3/16 inch hollow plastic tube. Alumina (WA-1, acidic) wasused as an inert diluent, and rhodizonate dye, disodium salt (from theSigma Chemical Company) was used as the dye. The inert diluent was mixedwith the dye in the ratios set forth in Table V. Table V also lists thequantity of fill used in the swab, together with the test results.

In performing the above examples, the swabs, after being filled with theabove-designated quantities of the above-designated ratios of filler anddye, were wetted with 1.5 ml. of 0.2M tartrate buffer, pH 2.8. The swabswere then rubbed on wood that had been previously painted with 0.5%lead-containing paint. In most instances, a positive reaction wasclearly visible within seconds, almost always within less than oneminute. A positive reaction is indicated by a deep pink color appearingon the absorbent ball of the swab.

                  TABLE VI                                                        ______________________________________                                        RATIO                                                                         ALUMINA:DYE                                                                              FILL (mg)   REACTIVITY                                             ______________________________________                                        100:1      40          All positive                                           100:1      80          All positive                                           80:1       40          All positive                                           80:1       80          All positive                                           60:1       40          All positive                                           60:1       80          All positive                                           40:1       30          All positive                                           40:1       40          All positive                                           40:1       80          All positive                                           20:1       40          All positive                                           20:1       80          All positive                                           10:1       40          50% positive-too much dye                               5:1       40          no reaction-too much dye                               ______________________________________                                    

Example XIV

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 40:1 was suspended in 0.2M tartrate buffer, pH 2.8. Thefollowing swabs: cotton, 6" plastic rod, from CitMed; rayon, 6" plasticrod, from CitMed; and dacron, 6" plastic rod, from CitMed, wereindividually dipped in the suspension. The dipped swabs were then rubbedon a piece of wood painted with a 0.5% lead-containing paint. Thesuspension lost activity rapidly, losing its ability to detect leadwithin one minute. It is interesting to note that the suspension lostactivity more rapidly when soaked onto the swab, as in this example,than when the mixture was filled through the center of the swab and thenwetted with the buffer.

Example XV

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 20:1 was suspended in 0.2M tartrate buffer, pH 2.8. Thefollowing swabs: cotton, 6" plastic rod, from CitMed; rayon, 6" plasticrod, from CitMed; and dacron, 6" plastic rod, from CitMed, wereindividually dipped in the suspension. The dipped swabs were then rubbedon a piece of wood painted with a 0.5% lead-containing paint. Thesuspension decayed at a rate slower than the suspension used in exampleXIV. Activity was still observed after five minutes.

Example XVI

A mixture of mannitol and rhodizonate dye, sodium salt at a ratio of20:1 was suspended in 0.2M tartrate buffer, pH 2.8. The following swabs:cotton, 6" plastic rod, from CitMed; rayon, 6" plastic rod, from CitMed;and dacron, 6" plastic rod, from CitMed, were individually dipped in thesuspension. The dipped swabs were then rubbed on a piece of wood paintedwith a 0.5% lead-containing paint. The suspension decayed at a rateslower than the suspension used in example XIV. Activity was stillobserved after five minutes.

TESTS TO DETERMINE SENSITIVITY OF REAGENT Example XVII

To determine the sensitivity of the test, a contoured wood molding stripwas divided into ten different sections. Each section was painted withlatex paint that was mixed with a different quantity of lead, rangingfrom 0.1% to 1.0%. The following diagram illustrates the various ratiosused:

    0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0.9% 1.0%

A swab with a 0.5 inch diameter absorbent ball made from rayon fibersand a 5/16 hollow plastic stem was filled with 40 mg. of alumina (WA-1,acidic) and rhodizonate dye, disodium salt (from the Sigma ChemicalCompany) in a 40:1 ratio. A 1.5 ml. solution of 0.2M tartrate buffer, pH2.8 was used as the developing agent. Within less than thirty seconds, adeep red color developed on the swab after rubbing the treated swab onthe wood section painted with 0.4% lead-containing paint. Similarlytreated swabs had equal or better results on all sections of the woodhaving a higher percentage of lead in the paint.

TESTS TO COMPARE RESULTS OF SWAB WITH RESULTS OF FILTER PAPER ExampleXVIII

For comparison with the swab test set forth in example XVII above, asimilar test was conducted using Whatman 3 mm. filter paper. A solutionwas prepared using 40 mg. of alumina (WA-1, acidic) and rhodizonate dye,disodium salt (from the Sigma Chemical Company) in a 40:1 ratio and a1.5 ml. solution of 0.2M tartrate buffer, pH 2.8. The filter paper wasdipped into the solution, allowing the solution to completely saturatethe filter paper. The saturated filter paper was then promptly rubbedover the wood painted with lead-containing paint.

The filter papers never clearly turned pink even when used on thesections of wood having high concentrations of lead. Hints of pink wereoccasionally visible at the edges of the filter paper; however,interpretation was very difficult. The wood underneath the filter paperdid become pink, but this pink color was only visible on the lightcolored paint, not on the dark paint. On the contoured wood surfaces itwas difficult to make good contact between the filter paper and thecontoured surfaces.

Example XIX

A swab with a 0.5 inch diameter absorbent ball made from rayon fibersand a 5/16 hollow plastic stem was filled with 40 mg. of alumina (WA-1,acidic) and rhodizonate dye, disodium salt (from the Sigma ChemicalCompany) in a 40:1 ratio. A 1.5 ml. solution of 0.2M tartrate buffer, pH2.8 was used as the developing agent, i.e., the swab was preparedexactly as set forth in example XVII, above. This time the swab wasrubbed on lead-glazed ceramic dishes. Within less than thirty seconds,the tip of the swab was obviously pink.

Example XX

A solution was prepared using 40 mg. of alumina (WA-1, acidic) andrhodizonate dye, disodium salt (from the Sigma Chemical Company) in a40:1 ratio and a 1.5 ml. solution of 0.2M tartrate buffer, pH 2.8. Apiece of Whatman 3 mm. filter paper was dipped into the solution,allowing the solution to completely saturate the filter paper, i.e., thefilter paper was prepared in accordance with the method set forth abovein example XVIII. The treated filter paper was rubbed on the lead-glazedceramic dishes used in example XIX. No detectable color was observed onthe filter paper after several minutes of contact with the lead-glazeddishes.

Example XXI

Plain untreated swabs having a rayon fiber absorbent ball of 0.5 inchdiameter on a 5/16 hollow plastic stem were soaked in a solution of 40mg. of alumina (WA-1, acidic) and rhodizonate dye, disodium salt (fromthe Sigma Chemical Company) in a 40:1 ratio and a 1.5 ml. solution of0.2M tartrate buffer, pH 2.8 , i.e., the same solution used in examplesXVIII and XX. When the swabs were then rubbed on the lead-glazed ceramicdishes, a clear positive result was easy to read.

Example XXII

Plain untreated swabs having a rayon fiber absorbent ball of 0.5 inchdiameter on a 5/16 hollow plastic stem were soaked in a solution of 40mg. of alumina (WA-1, acidic) and rhodizonate dye, disodium salt (fromthe Sigma Chemical Company) in a 40:1 ratio and a 1.5 ml. solution of0.2M tartrate buffer, pH 2.8 , i.e., the same solution used in examplesXVIII, XX, and XXI. When the swabs were then rubbed on the wood paintedwith at least 0.4% lead-containing paint, a clear positive result waseasy to read.

From the results of examples XVII through XXII, it is clear that theswab is far superior to the filter paper for effecting a test for thepresence of lead using rhodizonate dye.

COMPARISON OF DIFFERENT TYPES OF SWABS Example XXIII

A mixture of alumina (acidic) and rhodizonate dye, sodium salt at aratio of 40:1 was filled into the following swabs: cotton, 6" plasticrod, from CitMed; rayon, 6" plastic rod, from CitMed; and dacron, 6"plastic rod, from CitMed. About 3/16" to 1/4" of material was filled ineach swab. The swabs were then wetted with tartrate, sodium salt andrubbed on a wood board painted with a 0.5% lead-containing paint.

There were no notable differences in color intensity among the swabsmade of cotton, rayon, or dacron. The dacron and rayon swabs wettedwell, whereas the first few drops of buffer beaded on the surface of thecotton. During the rubbing stage, the dacron swab did not hold up aswell as the cotton and rayon swabs.

Example XXIV

A mixture of mannitol and rhodizonate dye, sodium salt at a ratio of20:1 was suspended in 0.2M tartrate buffer, pH 2.8. The following swabs:cotton, 6" plastic rod, from CitMed; rayon, 6" plastic rod, from CitMed;dacron, 6" plastic rod, from CitMed; molded foam from Coventry Mfg. Co.;spun foam from Coventry Mfge Co.; and 3" cotton tipped swabs fromJohnson & Johnson, were individually dipped in the suspension. Thedipped swabs were then rubbed on a piece of wood painted with a 0.5%lead-containing paint. The foam materials did not wet well, and littleor no color formation was observed on the material or the wood. Thecotton, rayon, and dacron swabs had intense color on the fibers. Under amicroscope it appeared that the fibers had been dyed. It did not appearas though a precipitate had been formed and trapped by the fibers.However, at high concentrations of lead and dye, some precipitate mayform. The precipitate is not necessary in order to detect a reaction.

The size of the absorbent ball on the swab also had little apparenteffect on the test results.

Example XXV

A swab with a hollow stem is filled with 30 mg of a mixture of4-nitronaphthalene-diazoamino-azo-benzene and an inert filler, aluminain ratios as shown in Table VI. The swab tip is wetted with an activatorsolution containing sodium potassium tartrate, sodium acetate, or sodiumcitrate at pH 8.5. The area to be tested is rubbed with the swab. Ifcadmium is present, the swab becomes pink.

Example XXVI

One crushable cartridge is filled with 30 mg Cadion,(1-(4-nitrophenyl)-3-(4-phenylazophenyl)triazine) and talc. Anotherbreakable cartridge is filled with 0.5 ml activator solution which is amixture of sodium tartrate, sodium acetate and sodium hydroxide. The pHof the activator solution is adjusted to be basic at a pH greater than9.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand the unit is shaken to ensure good mixing. The swab tip is rubbedover the area to be tested and becomes pink if cadmium is present.

TESTS FOR OTHER MATERIALS Example XXVII

A swab with a hollow stem is filled with 30 mg of a mixture of aurinetricarboxylic acid and an inert filler such as silica in ratios as shownin Table VI. The swab tip is wetted with an activator solutioncontaining dilute NaOH. The area to be tested is rubbed with the swab.If aluminum ion (Al⁺³) is present, the swab turns red.

Example XXVIII

One crushable cartridge is filled with 30 mg of a mixture of aurinetricarboxylic acid and an inert filler such as silica. Another breakablecartridge is filled with 0.5 ml of activator solution containing diluteNaOH.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand the unit is shaken to ensure good mixing. The swab tip is rubbedover the area to be tested and becomes red if aluminum (Al⁺³) ispresent.

Example XXIX

A swab tip is impregnated with the quinalizarin reagent by first soakingthe tip in a solution containing quinalizarin and then allowing the tipto air dry. Prior to use, the swab tip is wetted with a solution ofammonium hydroxide. The area to be tested is rubbed with the swab. Theswab tip is then developed by first exposing the tip to ammonia vaporsand then to glacial acetic acid vapors. If aluminum ion (Al⁺³) ispresent, the swab tip turns red to red-violet.

The quinalizarin reagent is prepared by dissolving 10 mg quinalizarin in2 ml pyridine and diluting with 18 ml acetone.

Example XXX

A swab tip is impregnated with the quinalizarin reagent by first soakingthe tip in a solution containing quinalizarin and then allowing the tipto air dry. One crushable cartridge (labelled A) is filled with 0.3 mlof concentrated ammonia solution. Another breakable cartridge (labelledB) is filled with 0.3 ml of glacial acetic acid.

The two cartridges are placed inside a larger cartridge having thequinalizarin impregnated swab tip at one end. When ready to use, thecrushable cartridge (A) containing the ammonia is broken first and theunit is gently squeezed to wet the swab tip. The swab tip is rubbed overthe area to be tested. Then the second cartridge (B) containing theglacial acetic acid is broken and the unit is gently squeezed to wet thetip with the acid. If aluminum ion (Al⁺³) is present, the swab tipdevelops a red to red-violet color.

The quinalizarin reagent is prepared by dissolving 10 mg quinalizarin in2 ml pyridine and diluting with 18 ml acetone.

Example XXXI

One crushable cartridge is filled with 0.5 ml of a 7% solution ofammonium sulfide. Another breakable cartridge is filled with 0.5 ml of0.1M NaOH. The swab tip is dyed blue or any dark color.

The two cartridges are placed inside a larger cartridge having the blueswab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing and gently squeezedto wet the swab tip. The swab tip is rubbed over the area to be testedand becomes white if aluminum ion (Al⁺³) is present.

Example XXXII

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of diphenylcarbazide and an inert filler such asalumina in ratios such as those shown in Table VI for lead. The swab tipis wetted with an activator solution containing 0.1N HCl or 0.1N HNO₃ atpH 2. The area to be tested is rubbed with the swab. If chromate ion(CrO⁴ ²⁻, hexavalent chromium) is present, the swab turns blue violet.

Example XXXIII

A swab attached to a solid stem or handle is impregnated withdiphenylcarbazide. The impregnated swab tip is wetted with an activatorsolution containing 0.1N HCl or 0.1N HNO₃ at pH 2. The area to be testedis rubbed with the swab. If chromate ion (CrO₄ ²⁻, hexavalent chromium)is present, the swab turns blue violet.

Example XXXIV

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofdiphenylcarbazide and an inert filler such as talc or alumina. Anotherbreakable cartridge is filled with 0.5 ml of activator solutioncontaining 0.1N HCl or 0.1N HNO₃ adjusted to pH 2.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and the area or swab or both becomeblue-violet if chromate ion (CrO₄ ²⁻ hexavalent chromium) is present.

Example XXXV

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of chromotropic acid(1,8-dihydroxynaphthalene-3,6-disulfonic acid) or its salt and an inertfiller such as alumina in appropriate ratios (like those shown in TableVI for lead). The swab tip is wetted with an activator solutioncontaining 0.1N nitric acid at pH 1-2. The area to be tested is rubbedwith the swab. If chromate ion (CrO₄ ²⁻, hexavalent chromium) ispresent, the swab turns red.

Example XXXVI

A swab attached to a solid stem or handle is impregnated withchromotropic acid (1,8- dihydroxynaphthalene-3,6-disulfonic acid) or itssalt. The impregnated swab tip is wetted with an activator solutioncontaining 0.1N nitric acid at pH 1-2. The area to be tested is rubbedwith the swab. If chromate ion (CrO₄ ²⁻ hexavalent chromium) is present,the swab turns red.

Example XXXVII

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofchromotropic acid (1,8-dihydroxyhaphthalene-3,6-disulfonic acid or itssalt) and an inert filler such as talc. Another breakable cartridge isfilled with 0.5 ml of activator solution containing 0.1N nitric acidadjusted to pH 1-2.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes red if chromate ion (CrO₄²⁻, hexavalent chromium) is present.

Example XXXVIII

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of alpha-nitroso-beta-naphthol and an inert filler suchas alumina in ratios as shown in Table VI. The swab tip is wetted withan activator solution containing 20% ethanol and 0.1N acetic acid at pH3. The area to be tested is rubbed with the swab. If nickel ion (Ni²⁺)is present, the swab turns brown.

Example XXXIX

A swab attached to a solid stem or handle is impregnated withalpha-nitroso-beta-naphthol. The impregnated swab tip is wetted with anactivator solution containing 20% ethanol and 0.1N acetic acid at pH 3.The area to be tested is rubbed with the swab. If nickel ion (Ni²⁺) ispresent, the swab turns brown.

Example XL

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofalpha-nitroso-beta-naphthol and an inert filler such as talc or alumina.Another breakable cartridge is filled with 0.5 ml of activator solutioncontaining 20% ethanol and 0.1N acetic acid adjusted to pH 3.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes brown if nickel ion (Ni²⁺)is present.

Example XLI

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of dimethylglyoxime (C₄ H₈ O₂ N₂) and an inert fillersuch as alumina in ratios as shown in Table VI. The swab tip is wettedwith an activator solution containing 20% ethanol and acetate ortartrate buffers at pH 4-5. The area to be tested is rubbed with theswab. If nickel ion (Ni²⁺) is present, the swab turns red.

Example XLII

A swab attached to a solid stem or handle is impregnated withdimethylglyoxime (C₄ H₈ O₂ N₂). The impregnated swab tip is wetted withan activator solution containing 20% ethanol and acetate or tartratebuffers at pH 4-5. The area to be tested is rubbed with the swab. Ifnickel ion (Ni²⁺) is present, the swab turns red.

Example XLIII

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofdimethylglyoxime (C₄ H₈ O₂ N₂) and an inert filler such as talc. Anotherbreakable cartridge is filled with 0.5 ml of activator solutioncontaining 20% ethanol and acetate or tartrate buffers adjusted to pH4-5.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab is rubbedover the area to be tested and becomes red if nickel ion (Ni²⁺) ispresent.

Example XLIV

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of sodium bismuthate (NaBiO₃) and an inert filler suchas alumina in ratios as shown in Table VI. The swab tip is wetted withan activator solution containing 0.2N nitric acid or 0.2N sulfuric acid.The area to be tested is rubbed with the swab. If manganese ion (Mn²⁺)is present, the swab turns purple.

Example XLV

A swab attached to a solid stem or handle is impregnated with sodiumbismuthate (NaBiO₃). The impregnated swab tip is wetted with anactivator solution containing 0.2N nitric acid or 0.2N sulfuric acid.The area to be tested is rubbed with the swab. If manganese ion (Mn²⁺)is present, the swab turns purple.

Example XLVI

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofsodium bismuthate (NaBiO₃) and an inert filler such as talc. Anotherbreakable cartridge is filled with 0.5 ml of activator solutioncontaining 0.2N nitric acid or 0.2N sulfuric acid.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes purple if manganese ion(Mn²⁺) is present.

Example XLVII

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of mercury (II) chloride, ammonium thiocyanate, andcopper sulfate and an inert filler such as alumina in ratios as shown inTable VI. The swab tip is wetted with an activator solution containing0.05N sulfuric or acetic acid. The area to be tested is rubbed with theswab. If zinc ion (Zn²⁺) is present, the swab turns violet.

Example XLVIII

A swab attached to a solid stem or handle is impregnated with a mixtureof mercury (II) chloride, ammonium thiocyanate, and copper sulfate. Theimpregnated swab tip is wetted with an activator solution containing0.05N sulfuric or acetic acid. The area to be tested is rubbed with theswab. If zinc ion (Zn²⁺) is present, the swab turns purple.

Example XLIX

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofmercury (II) chloride, ammonium thiocyanate, and copper sulfate and aninert filler such as talc. Another breakable cartridge is filled with0.5 ml of activator solution containing 0.05N sulfuric or acetic acid.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes purple if zinc ion (Zn²⁺)is present.

Example L

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of sodium rhodizonate and an inert filler such asalumina in ratios as shown in Table VI. The swab tip is wetted with anactivator solution containing a neutral buffer such as 0.1M (or otherbuffer concentrations) phosphate adjusted to pH 7. The area to be testedis rubbed with the swab. If barium ion (Ba²⁺) is present, the swab turnsreddish brown.

Example LI

A swab attached to a solid stem or handle is impregnated with sodiumrhodizonate. The impregnated swab tip is wetted with an activatorsolution containing a neutral buffer such as 0.1M (water or other bufferconcentrations) phosphate adjusted to pH 7. The area to be tested isrubbed with the swab. If barium ion (Ba²⁺) is present, the swab turnsreddish brown.

Example LII

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofsodium rhodizonate and an inert filler such as talc. Another breakablecartridge is filled with 0.5 ml of activator solution containing aneutral buffer such as 0.1M (other buffer concentrations and water canbe used) phosphate adjusted to pH 7. Other pHs in the range 2 to 10 canbe used.

The two cartridges are placed inside a larger cartridge having a swabtip at one end. When ready to use, the breakable cartridges are brokenand the unit is shaken to ensure good mixing. The swab tip is rubbedover the area to be tested and becomes reddish brown if barium ion(Ba²⁺) is present.

Example LIII

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of sodium rhodizonate, potassium chromate and an inertfiller such as alumina in ratios as shown in Table VI. The swab tip iswetted with an activator solution containing a neutral buffer such as0.1M (or other concentration of buffer) phosphate adjusted to pH 7(other neutral buffers can be used as well). The area to be tested isrubbed with the swab. If strontium ion (Sr²⁺) is present, the swab turnsreddish brown.

Example LIV

A swab attached to a solid stem or handle is impregnated with sodiumrhodizonate. The impregnated swab tip is wetted with an activatorsolution containing a neutral buffer such as 0.1M phosphate adjusted topH 7 (other concentrations of buffer, other neutral buffers and watercan be used) and potassium chromate. The area to be tested is rubbedwith the swab. If strontium ion (Sr²⁺) is present, the swab turnsreddish brown.

Example LV

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofsodium rhodizonate, potassium chromate and an inert filler such as talc.Another breakable cartridge is filled with 0.5 ml of activator solutioncontaining a neutral buffer such as 0.1M phosphate adjusted to pH 7(other concentrations of buffer, other neutral buffers and water can beused).

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes reddish brown if strontiumion (Sr²⁺) is present.

Example LVI

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of p-dimethylaminobenzylidene-rhodanine and an inertfiller such as alumina in ratios as shown in Table VI. The swab tip iswetted with an activator solution containing dilute nitric acid (0.1N).The area to be tested is rubbed with the swab. If silver ion (Ag⁺) ispresent, the swab turns red-violet.

Example LVII

A swab attached to a solid stem or handle is impregnated withp-dimethylaminobenzylidene-rhodanine. The impregnated swab tip is wettedwith an activator solution containing dilute nitric acid (0.1N). Thearea to be tested is rubbed with the swab. If silver ion (Ag⁺) ispresent, the swab turns red-violet.

Example LVIII

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) ofp-dimethylaminobenzylidene-rhodanine and an inert filler such as talc.Another breakable cartridge is filled with 0.5 ml of activator solutioncontaining dilute nitric acid (0.1N).

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes red-violet if silver ion(Ag⁺) is present.

Example LVIV

A swab with a hollow stem or handle is filled with 30 mg (range 15 to 50mg) of a mixture of tannic acid and an inert filler such as alumina inratios as shown in Table VI. The swab tip is wetted with an activatorsolution containing 0.1M ammonium acetate at pH 5. The area to be testedis rubbed with the swab. If vanadium as the vanadate ion (VO₃ ²⁻) ispresent, the swab turns deep blue to blue black.

Example LX

A swab attached to a solid stem or handle is impregnated with tannicacid. The impregnated swab tip is wetted with an activator solutioncontaining 0.1M ammonium acetate at pH 5. The area to be tested isrubbed with the swab. If vanadium as the vanadate ion (VO₃ ²⁻) ispresent, the swab turns deep blue to blue black.

Example LXI

One crushable cartridge is filled with 30 mg (range 15 to 50 mg) oftannic and an inert filler such as talc. Another breakable cartridge isfilled with 0.5 ml of activator solution containing 0.1M ammoniumacetate adjusted to pH 5.

The cartridges (two or more) are placed inside a larger cartridge havinga swab tip at one end. When ready to use, the breakable cartridges arebroken and the unit is shaken to ensure good mixing. The swab tip isrubbed over the area to be tested and becomes deep blue to blue black ifvanadium as the vanadate ion (VO₃ ²⁻) is present.

One of ordinary skill in the art would appreciate that all of thereagents disclosed herein and in the patents and applicationsincorporated herein by reference may be used to detect a substance ofinterest using any of the structures disclosed herein. In addition, oneof ordinary skill in the art would appreciate that water may be used asan activator in cases when the dye is water soluble.

Although only preferred embodiments are specifically illustrated anddescribed herein, it will be appreciated that many modifications andvariations of the present invention are possible in light of the aboveteachings and within the purview of the appended claims withoutdeparting from the spirit and intended scope of the invention.

What is claimed is:
 1. A swab device for testing for a metal on asurface, comprising:a hollow stem; an absorbent ball of material mountedat one end of the stem; a passageway interconnecting an interior of saidhollow stem with said absorbent ball of material; a first crushablecartridge within said stem interior; a second crushable cartridge withinsaid first crushable cartridge; a reagent that reacts with the metal insuch a manner so as to give a visual indication of the reaction, saidreagent being located within one of the first and second crushablecartridges; and an activator solution for activating the metal, saidactivator solution being located in the other of said first and secondcrushable cartridges, wherein said metal is selected from the groupconsisting of chromium, nickel, manganese, zinc, barium, strontium,silver and vanadium.
 2. The swab device of claim 1, wherein saidabsorbent ball of material is fibrous.
 3. A method of testing for ametal on a surface, comprising the steps of:providing a swab stickhaving a stem and an absorbent ball of material at one end of the stem,wherein the absorbent ball of material is impregnated with an activatingsolution that reacts with the metal; contacting the impregnatedabsorbent ball of material with the surface; impregnating the absorbentball of material with a reagent that reacts with the metal in such amanner so as to give a visual indication of the reaction; detecting thepresence of the metal by inspecting the impregnated ball of material forthe visual indication; wherein the metal is selected from the groupconsisting of chromium, nickel, manganese, zinc, barium, strontium,silver and vanadium.
 4. The method of claim 3, wherein said absorbentball of material is fibrous.
 5. The method of claim 3, wherein saidmetal is chromium.
 6. The method of claim 3, wherein said metal isnickel.
 7. The method of claim 3, wherein said metal is silver.